| Atmospheric pollutants have adverse effects on human health, are the cause of acid rain and visibility reduction, and influence the energy balance of the planet. Models that accurately describe the physical and chemical atmospheric transformations of these pollutants are necessary to determine how changing emissions will affect downwind airborne concentrations and how to select the best strategy to control air pollution. However, modeling atmospheric aerosols is quite challenging because of the complexity of the corresponding physical and chemical processes in the atmosphere. In the first part of this work, a set of equilibrium, dynamic, and hybrid approaches for the modeling of aerosol dynamics is evaluated. A linear interpolation scheme is proposed for the mapping of the moving aerosol size/composition distribution onto a fixed size grid. Although the dynamic approach is most accurate, it is more computationally intensive than the equilibrium method. The hybrid approach combines accuracy with computational efficiency. Next, integrated approaches to modeling both organic and inorganic components in the atmospheric aerosols are presented. An improved weighting scheme for the bulk equilibrium approach is proposed. Water absorption by secondary organic aerosol (SOA) is investigated. Finally, a three-dimensional chemical transport model which incorporates the aerosol modules developed in this study is applied to the eastern United States and evaluated against the measurement data from the Pittsburgh Air Quality Study (PAQS). |
